"In the bordering village ... the situation started heating up last night when according to the residents of this village said that they heard a series on gun shots and artillary coming towards the village ... And according to them it was not just Abkhazians but also Russians soldiers patroling the area.

"Right now the village is calm, EU monitors are controlling the situation."

Shota Utiashvili, an interior ministry spokesman, told the AFP news agency: "This was clearly aimed at the police because they knew the police would go there to investigate."

However, Steve Bird, a spokesman for the EU monitoring mission, said that it was too early to say who and what caused the explosion

"Its something for the Georgian police to investigate and that will take them some time to do," he said.

"We have no further information as yet as to the origin of the explosion, who might have been involved with it, I think it's too early to say."

'Evil power'

Mikheil Saakashvili, the Georgian president, called a meeting of the national security council after the attack.

"We are faced with an evil power," he said in televised comments from the council session. "They are very disappointed they could not take Tbilisi and the whole of Georgia. That's why the risks remain high."

The village was the location of a Russian checkpoint during the war with Georgia in August, before Russia pulled back its troops.

Russia entered Georgia in August to support the South Ossetia separatist movement in the north of the country.

South Ossetia and Abkhazia declared independence from Georgia in the early 1990s, however only a few nations, including Russia, recognises their authority.

A French-brokered ceasefire deal saw Russian troops withdraw in October from buffer zones around the two regions.